I've never been a master of modeling and model painting. That's why I've chosen black primer for my first Deathwing Squad. It didn't take so long for me to understand I was in big trouble. Trying to paint chaos white over black primer was not very relieving.
I asked few friends, made some web search and I learned I had to use white primer for Deathwing.
Scraping black primer wasn't easy for me. I couldn't take the whole primer off but maybe 90 percent.
Than I tried to follow some tips from friends and web. I finished my first Deathwing squad. They look horrible. Anyway I liked them that way too. So I paint freehand squad insignia on shoulder pads to give them a unique look. After all work has done, some of my friends from my gaming club said they liked the way they look. One of my friend said "These look like they've just made a deep strike"...